Improvements on laser scanned storage phosphors systems have been described by Nelson, in the above referenced copending application, principally by increasing the thickness of the phosphor screen or the use of two screens to improve x-ray stopping power. In addition, methods of weighting the relative importance of the output signals collected during scanning by the two laser beams were described.
Problems arise due to the poor optical coupling efficiency between phosphor and photomultiplier tube through the use of a long, linear array of fiber optics. This may introduce additional noise into the signal if the storage phosphor has poor conversion efficiency from x-ray energy into an optical signal. In some cases a faster read out may be desired, which is possible with a line-scan format but difficult to achieve with a point-scan format and a single photomultiplier tube.